368 
PALAEONTOLOGY OF NEW YORK. 
Beaks in advance of the anterior third, prominent and incurved. Umbonal 
slope not defined. 
Surface marked by fine concentric striae and by angular, somewhat distant, 
concentric folds, which become obsolete on the middle and posterior parts 
of the shell. Interior unknown. 
Two valves of equal size have lengths of 14 mm. and heights of 10 mm. 
Formation and locality. In the shales of the Hamilton group, York, Living¬ 
ston county, N. Y. 
Gkammysia Eriopia. 
PLATE LXIII, FIGS. 7, 8. 
Cardiomorplia Eriopia, Hall. Prelim. Notice Lamellibrancliiata, 2, p. 92. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 63, figs. 7, 8. 1883. 
Shell above the medium size, sub-circular or very broadly ovate; length about 
one-fifth greater than the height; basal margin regularly rounded into the 
broad posterior end. Cardinal line declining toward the posterior extremity. 
Anterior end short, abruptly rounded below the lunule. 
Valves regularly convex below and posteriorly, gibbous in the middle 
and above. 
Beaks at the anterior third or fourth, prominent and strongly incurved. 
Umbonal ridge merging into the general convexity of the shell. Post¬ 
cardinal slope marked by a low ridge which may become obsolete. 
Surface marked by fine concentric striae and by fine, distant, radiating 
striae, principally developed on the posterior slope. Also marked by strong, 
concentric folds which are principally shown on the umbo and the anterior 
portion of the valve. In young shells the undulations are present on the 
posterior slope, limited above by the post-cardinal ridge. Interior unknown. 
A small specimen has a length of 21.5 mm. and a height of 17 mm. A 
larger individual has a length of 55 mm. 
This species bears some resemblance to G. obsoleta, but there is an absence 
of any anterior radiating folds, the beak is more erect and the concentric 
